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b=plgPosJmyNrihEruAuxGCovWsINyDoKANVz0XOMKin6rFfsUaVSni5gxpvz4m5LoH 5SIxGh/M5Jwkwu7vTPD5eNoVHxxlnmQhY2TQXJRM06mq1hHRyEna0m1L3Pn1QEQ6fT hxDEkvFqLPrcwXHfzLRHoNTPUt190O9W51n/Pm8oVHZoQa+BvVCblFHoLqi1kh0F8i Md38l/OqgeVdMTgzpblxzuLx2TDpT6VqOeFWN4P23AXyhxsI8cnk+YFwKr/fJ/1pvV J5flClImwPyPm3LDAXIq5IK4VSxxXjpRem6/OdZiBVEcl+IJT/qBncrXUSJxq28vUq mNc6vtJGLHw1Q== From: SeongJae Park To: Luiz Capitulino Cc: SeongJae Park , david@redhat.com, willy@infradead.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lcapitulino@gmail.com, shivankg@amd.com Subject: Re: [PATCH 2/3] proc: kpagecount: use snapshot_page() Date: Fri, 27 Jun 2025 11:30:56 -0700 Message-Id: <20250627183056.52582-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <5e94d287b6174098938ddd9959cf3c0619fb610a.1750961812.git.luizcap@redhat.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: pk5en74zo7bdjjas9umcyx6gdsmigg6t X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B84A6100006 X-Rspam-User: X-HE-Tag: 1751049060-404741 X-HE-Meta: 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 V87rgUSH uusxF6fDSLf1LK5TvbwXzQ+ROiyT1FrffFEosfeBCjgQcjdxkzlS/Q+kjXpOQfPDwleOGssD7RiJqBwLkF1cGxtUBCwtjsyXQQL20B7TF27pC2K+yX9M1O2397BS4BRfMkyx//DVkGTTALaRWvhbADGZK70crmqN8mdqKQ5aWkDPcbdh6LoaaKpoxekNZO6FcVOACC1RA1jxU6yr/F8pOxK9KDpnzTrOjwQzy+JdvzECLR0H6cPaB7Qs3+/fpihWMUjQk7KPko7FZyeuFYdwkXbQ86Kve+KvcTRyrjyq1Jiwkq+I= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 26 Jun 2025 14:16:52 -0400 Luiz Capitulino wrote: > Currently, the call to folio_precise_page_mapcount() from kpage_read() > can race with a folio split. When the race happens we trigger a > VM_BUG_ON_FOLIO() in folio_entire_mapcount() (see splat below). > > This commit fixes this race by using snapshot_page() so that we > retreive the folio mapcount using a folio snapshot. [...] > Signed-off-by: Luiz Capitulino Acked-by: SeongJae Park Thanks, SJ [...]